I make my own pizza at home. Cost of ingredients per 18" pie... probably less than $5 depending on the toppings. I'm sure running the oven costs about a buck for a pizza, so divide that by however many pizzas I'm making (usually 2).
Dough - total cost: Probably about a buck (made from scratch, includes yeast, flour, herbs, oil, salt and sugar)
Sauce - total cost: Probably about $0.50 (made from scratch, using organic canned tomato sauce, herbs, salt and sugar)
Cheese - total cost: Probably about $2-$3 depending on what I buy. Generally I use about 1/2lb to 3/4lb of cheese per pie, and a 2lb bag generally costs about $7 at the grocery store (less if I buy "bulk" at Costco).
Toppings - total cost: varies. I would venture a couple bucks worth of toppings. My kids and wife like pineapple, so we generally use a whole can. We get turkey pepperoni, which probably costs $4 per package, but lasts across about 6 pizzas or so.
A dash of cornmeal and some crisco on the stone are probably a couple pennies. My pizzas are definitely not "the best" category, but we (and friends that have had them) like them as much as or better than most chain pizza shops. I personally have had better pizza only once before at a small independent NY Pizzeria in Warsaw NY. Haven't had anything as good since. But honestly, when I can make a pie at home from ingredients that I know are healthy without any mysteries in them that my family genuinely enjoys for about $6 a pie and have fun doing it... there's no reason to pay $13 or more for someone else to make me one.